Method to evaluate the L/D Ratio of Neutron Imaging Beams

Pugliesi, R.; Pereira, M. A. Stanojev; Schoueri, Roberto Mauro

doi:10.15392/bjrs.v5i1.257

“…Two circular 5 cm and 6 cm diameter beams, travelling in the negative z direction, were used to simulate both operation modes. The L/D ratios, where L is the distance between the entrance aperture of the beam to the image plane (detector box scintillator screen) and D is the diameter of the beam aperture 34 , are 1000 and 500 for the bottom and top pinhole, respectively.…”

Section: Methodsmentioning

confidence: 99%

A Monte Carlo model of the Dingo thermal neutron imaging beamline

Jakubowski

¹

,

Chacon

²

,

Tran

³

et al. 2023

Preprint

0

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In this study, we present a validated Geant4 Monte Carlo simulation model of the Dingo thermal neutron imaging beamline at the Australian Centre for Neutron Scattering. The model, constructed using CAD drawings of the entire beam transport path and shielding structures, is designed to precisely predict the in-beam neutron field at the position at the sample irradiation stage. The model’s performance was assessed by comparing simulation results to various experimental measurements, including planar spatial thermal neutron distribution obtained in-beam using gold foil activation and 10B4C-coated microdosimeters and the out-of-beam neutron spectra measured with Bonner spheres. The simulation results demonstrated that the predicted neutron fluence at the field’s centre is within 8.1% and 2.1% of the gold foil and 10B4C-coated microdosimeter measurements, respectively. The logarithms of the ratios of average simulated to experimental fluences in the thermal (Eth < 0.414 eV), epithermal (0.414 eV < Eepi < 11.7 keV) and fast (Efast > 11.7 keV) spectral regions were approximately -0.03 to +0.1, -0.2 to +0.15, and -0.4 to +0.2, respectively. Furthermore, the predicted thermal, epithermal and fast neutron components in-beam at the sample stage position constituted approximately 18%, 64% and 18% of the total neutron fluence.

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“…Two circular 5 cm and 6 cm diameter beams, travelling in the negative z direction, were used to simulate both operation modes. The L / D ratios, where L is the distance between the entrance aperture of the beam to the image plane (detector box scintillator screen) and D is the diameter of the beam aperture 44 , are 1000 and 500 for the bottom and top pinhole, respectively. The distance between the collimator entry and the centre of the sample stage assembly in the model, where the in-beam scoring plane is located, is 990 cm.…”

Section: Methodsmentioning

confidence: 99%

A Monte Carlo model of the Dingo thermal neutron imaging beamline

Jakubowski,

Chacon,

Tran

et al. 2023

Sci Rep

2

0

View full text Add to dashboard Cite

In this study, we present a validated Geant4 Monte Carlo simulation model of the Dingo thermal neutron imaging beamline at the Australian Centre for Neutron Scattering. The model, constructed using CAD drawings of the entire beam transport path and shielding structures, is designed to precisely predict the in-beam neutron field at the position at the sample irradiation stage. The model’s performance was assessed by comparing simulation results to various experimental measurements, including planar thermal neutron distribution obtained in-beam using gold foil activation and $$^{10}$$ 10 B$$_{4}$$ 4 C-coated microdosimeters and the out-of-beam neutron spectra measured with Bonner spheres. The simulation results demonstrated that the predicted neutron fluence at the field’s centre is within 8.1% and 2.1% of the gold foil and $$^{10}$$ 10 B$$_{4}$$ 4 C-coated microdosimeter measurements, respectively. The logarithms of the ratios of average simulated to experimental fluences in the thermal (E$$_{th}<$$ th < 0.414 eV), epithermal (0.414 eV < E$$_{epi}<$$ epi < 11.7 keV) and fast (E$$_{fast}>$$ fast > 11.7 keV) spectral regions were approximately − 0.03 to + 0.1, − 0.2 to + 0.15, and − 0.4 to + 0.2, respectively. Furthermore, the predicted thermal, epithermal and fast neutron components in-beam at the sample stage position constituted approximately 18%, 64% and 18% of the total neutron fluence.

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“…The optical setup was defined by the L/D ratio of 400. The L/D ratio (ratio of L being the distance between the entrance aperture of the beam to the image plane over D that is the diameter of the beam aperture) represents a key factor determining the quality of the resolution [45]. The bigger the L/D ratio, the lower the angular resolution of the neutron beam and the better the resolution.…”

Section: Methodsmentioning

confidence: 99%

Neutron Radiography Study of Laboratory Ageing and Treatment Applications with Stone Consolidants

Ban

¹

,

Kock

²

,

Ott

³

et al. 2019

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A nano-silica consolidant and nano-titania modified tetraethyl-orthosilicate were applied on two building stones, a carbonate and a silicate, by brush, poultice or capillary absorption. Neutron radiography was used to monitor capillary water absorption, and to analyse changes in physical properties caused by heat treatment of specimens for the purposes of artificially ageing and different treatment applications with stone consolidants. Moreover, ultrasonic pulse velocity and gravimetrically determined water absorption were analysed to cross-validate neutron radiography. The results reveal that reactive systems like tetraethyl-orthosilicates need an unknown period for polymerisation, which makes nano-silica consolidants more favourable for construction follow-up work. While polymerisation is incomplete, hydrophobic behaviour, water trapping and pore clogging are evident. Within the tetraethyl-orthosilicate treatment, poultice and brushing are strongly influenced by the applicant, which results in wide ranging amounts of water absorbed and anomalous water distributions and kinetics. The carbonate lithotype displays polymerisation initiated in the core of the specimen, while the lateral surfaces are still mostly hydrophobic. Reaction time differences can be attributed to the different amounts of consolidants applied, which is a result of the chosen application settings. Artificial ageing of stone specimens is a prerequisite when mechanical strength gain is studied, as demonstrated by sound speed propagation.

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Method to evaluate the L/D Ratio of Neutron Imaging Beams

Cited by 3 publications

References 1 publication

A Monte Carlo model of the Dingo thermal neutron imaging beamline

A Monte Carlo model of the Dingo thermal neutron imaging beamline

A Monte Carlo model of the Dingo thermal neutron imaging beamline

Neutron Radiography Study of Laboratory Ageing and Treatment Applications with Stone Consolidants

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